function s1_generate_a_series_of_files() {
	for i in {1..100}; do
		echo $i > /tmp/new_file$i
	done
}
function s2_list_4_files_in_long_format_about_account_and_group() {
	ls -l /etc/{passwd,shadow,group,gshadow} | sort -d
}
function s3_find_items_related_to_given_username() {
	grep -h $1 /etc/{passwd,shadow} | sort -d
}
function s4_find_items_related_to_given_group_name() {
	grep -h $1 /etc/{group,gshadow} | sort -d
}
function s5_create_groups_for_given_group_names() {
	groupadd rnd && groupadd itoperation
}
function s6_create_users_and_set_their_group_as_required() {
	useradd -G rnd adam && useradd -G rnd bob && useradd -G itoperation calvin && useradd -G itoperation david && useradd -G rnd edward
}
function s7_change_users_shell() {
	usermod -s /usr/bin/sh adam && usermod -s /usr/bin/sh edward
}
function s8_set_password_change_policy() {
	passwd -n 10 -x 60 -w 10 adam
	passwd -n 10 -x 60 -w 10 bob
	passwd -n 10 -x 60 -w 10 david
	passwd -n 10 -x 60 -w 10 calvin
	passwd -n 10 -x 60 -w 10 edward
}
function s9_set_password_for_five_users() {
    usernames=("adam" "bob" "calvin" "david" "edward") 
    if [ -z "$1" ]; then
        echo "错误：请提供密码参数" >&2
        return 1
    fi
    for i in $(seq 1 5); do
        echo "${usernames[$((i-1))]}:$1" | chpasswd
    done
}
function s10_lock_bobs_password() {
	usermod -L bob
}
function s11_include_adam_into_wheel_group() {
    if [ "$(id -u)" -ne 0 ]; then
        echo "错误：请使用root权限执行" >&2
        return 1
    fi
    usermod -a -G wheel adam
}

function s12_change_files_permission() {
    for i in {1..33}; do
        chmod 640 "/tmp/new_file$((i*3))"
        restorecon "/tmp/new_file$((i*3))" 2>/dev/null 
    done
}
